Process and apparatus for the thermal cracking of liquid or gaseous hydrocarbons



Sept. 19, 1961 s. LARCHER ETAL 3,000,989

PROCESS AND APPARATUS FOR THE THERMAL CRACKING 0F LIQUID OR GASEOUS HYDROCARBONS Filed June 24, 1959 H YDROCARBO/V H YDROCA HBO/V United States Patent "ice PROCESS AND APPARATUS FOR THE THERMAL CRACKING 0F LIQUID 0R GASEOUS HYDRO- CARBONS Silvio Larcher, Milan, and Mario Compostella, Terni, Italy, assignors to Montecatini, Societa Generale per llndustria Mineraria e Chimica, Milan, Italy, a corporation of Italy Filed June 24, 1959, Ser. No. 822,696 Claims priority, application Italy June 27, 1958 12 Claims. (Cl. 260--679) This invention relates to an improvement in processes and apparatus for thermally cracking hydrocarbons, such as parafiinic, olefinic and aromatic hydrocarbons, to obtain other saturated or unsaturated hydrocarbons of lower molecular weight. It particularly relates to a process for the thermal cracking of paraflinic, olefinic and aromatic hydrocarbons by which other unsaturated and aromatic hydrocarbons having a low molecular weight, in particular acetylene, ethylene, propylene, butadiene, and benzene can be obtained in high yields. The characteristics of a number of the known processes are summarized as follows:

1) In the electric arc process the hydrocarbon is cracked by an electric are which supplies the heat needed for the endotherrnal cracking reaction of the hydrocarbon molecules. This process requires so high a consumption of electric energy that its economic advantages for preparing acetylene from carbide are limited. Moreover, the potential capacity of a single unit of this type cannot be increased above a certain limit. When high commercial production is needed, a substantial number of such units, operated in parallel, are required.

(2) A cyclic process has been proposed which involves successively heating a chamber filled with refractory to about 1500 C., by means of combustion gases, stopping the heating and passing the hydrocarbons to be cracked in contact with the hot refractory materials. The heating and the passage of the hydrocarbons are then repeated. Furnaces of this type cannot operate continuously. Therefore the temperature varies during the cracking process, and high yields cannot be obtained.

(3) According to another known process the heat needed for cracking it supplied by partial combustion of the same hydrocarbon that is being cracked. It can be used to produce actylene and ethylene from methane. A single big flame is used in this process. This results in the formation of zones having different temperatures both in the longitudinal and in the transverse sections of the flame. Here also high yields of unsaturated hydrocarbons are not obtainable.

(4) There has finally been proposed a thermal cracking process in which the preheated hydrocarbons to be cracked are passed through an oxidizing flame at high temperature, the flame being obtained by combustion of oxygen with a combustible gas, such as hydrogen, methane, propane, or the like. The big flame of circular section employed in this process has, in part, the same disadvantages as in the preceding process. The hydrocarbon to be cracked is subjected to markedly different or varying thermal conditions or treatment, since this depends upon the path of the hydrocarbon through the flame. The flame has a very irregular temperature distribution. Using a venturi tube improves the temperature distribution but does not make it possible to avoid the inconveniences and disadvantages inherent in the use of big flames.

The said prior cracking processes, which use combustion gases as the source of heat, thus operate with big flames, so that due to the great width of the flame each molecule of hydrocarbon to be cracked cannot be subjected to a uniform thermal action. The thermal action is determined by the temperature and contact time with the flame. As a consequence low yields are obtained. Also, the attempt to make the thermal action uniform by mixing with turbulent flow does not offer substantial ad vantages. The excessive thermal action on some molecules causes a higher cracking, resulting in the formation of carbon black and hydrogen, while the deficient thermal action on other molecules causes a low cracking resulting in unreacted hydrocarbon or, in any case, in a low yield.

In order to eliminate the aforementioned causes which are inherent in the processes adopted until now for cracking hydrocarbons, we have devised and tested a special process and apparatus based on the following principles:

(1) The heat source, which is at a very high temperature (2000-3000 C.), is kept separate from the hydrocarbon to be cracked. a

(2) The heat source is in the form of a lamina or sheet formed or consisting of the combustion products of the flame. By the term lamina or sheet we intend a stream of hot gases, having a preferably constant rectangular cross-section, wherein all the points of any crosssectional area have substantially the same temperature. To obtain this one must operate the burner in such a manner as to produce perfect combustion in a very limited space. Moreover it permits the products of combustion to mix perfectly in such a way as to bring about uniformity in their temperature.

The combustion chamber is ideally divided into two zones:

(a) Combustion zone-Its length is such as to permit the perfect combustion of the introduced gases. Therefore, it has a length which depends upon the type of burner employed and on the characteristics of the com,- bustible gas as well as of the combustion-supporting gas, and also on the ratio of their flow rates. That length may be identical with the length of the flame produced.

(b) Temperature-uniforming z0ne.-As a consequence of the high speed of the gases, and their strong vortex movement, vigorous mixing of the products of combustion occurs in this zone.

We have found experimentally that the most effective combustion chambers have a potentiality of between 5 and 25.10 KcaL/cubic meter and that the speeds of the gases at the outlet must be of the order of to m./sec. The most effective combustion chambers have a trapezoidal cross-section, the smaller base being at the outlet-side, that is, they are tapered from inlet toward outlet.

(3) The hydrocarbon to be cracked is fed in the vapor or gaseous state, as a lamina or sheet.

By lamina or sheet of hydrocarbon we intend a stream of hydrocarbon in the state of vapour or gas, of limited thickness, and having high speed and uniform temperature and composition. Its Reynolds number should be such as to ensure turbulence.

(4) The hydrocarbon lamina or sheet must be brought to intersect the lamina of hot combustion gas, at an ap propriate angle of incidence and with appropriate speed. In fact the hydrocarbon should penetrate uniformly into and distribute itself uniformly Within the hot gas; this is favoured by the turbulence of the latter. Hence the hydrocarbon should have a speed and kinetic energy depending upon the speed and kinetic energy of the lamina or sheet of hot combustion gas.

The new process can be carried out with the widest range of outflow rate, either of the gases constituting the heat source or of the gases or vapors to be cracked, since it is not necessary to prevent backfire. This permits or results in increases in the outflow rate. The new process makes it possible to vary the outflow rate, and therefore the reaction time, for a furnace of given size in accordance with, or as a function of, the specific characteristics of the hydrocarbon to be cracked. The feasibility and ease of control of the temperatures and of the contact times makes it possible to displace the equilibrium of the cracking reaction towards the production of desired hydrocarbons. r

The accompanying drawing illustrates a preferred embodiment of the invention:

FIG. 1 is a front elevation, partly in vertical section, of an apparatus utilizable for production of acetylene and ethylene;

FIG. 2 is a vertical section of the apparatus of FIG. 1, the section being in a plane perpendicular to the plane of FIG. 1.

Into the central part 1 of the water-cooled metallic burner is conveyed, for example, the combustion supporter, i.e. oxygen, and into the hollow space 2, the combustible. However, it is possible to introduce the fuel at inlet 1. At the burner outlet the combustion supporter mixes with the fuel, a flame being fired having the shape of a lamina or sheet. The burner is extended in the direction normal to the plane of the drawing. The fuel and the combustion supporter exit from the slits 3-4, which have openings extending a few millimeters in the plane of FIG. 2, and which also extend normally to said plane. In the refractory walled 'e,000,9se I ,r

combustion chamber 5, the combustion is completed and V the gas lamina or sheet is formed. The hot gases leaving the combustion chamber enter the reaction chamber 8, also made of refractory materials, being collided or intersected laterally by two laminae or sheets of hydrocarbon vapors or gases which are introduced from conduits 11 and 12. The sheets are conveyedagainst both sides of the hot gas lamina by nozzles 6 and 7 each of which is in the form of a wide slit extending normal to the plane of FIG. 2, analogously to the burner and the combustion chamber 5. The position of nozzles 6, 7 and of burner 1, 2 can be reversed. A number of burners can be mounted in place of the inlet nozzles 6, 7, and an inlet nozzle for hydrocarbon to be cracked can be mounted in place of burner 1. Also, a refractory burner may be used.

Into the cracking chamber 8, the perfectly homogeneous mixture formed of hot gases and of the hydrocarbon enters, and stays therein for the time necessary for reacting.

The exit gases from 8 are abruptly chilled in lower chamber 10 by cold water introduced at 9. Abrupt chilling is necessary to stabilize the products of reaction, which would otherwise decompose.

The laminar shape makes it possible to extend the apparatus of FIGS. 1 and 2 in the direction perpendicular to the plane of FIG. 2, without altering or adversely affecting the high yields of acetylene and ethylene.

The operation of the furnace described is very flexible because it is possible to employ therein the most varied combustible and combustion-supporting gases and the most varied hydrocarbons, provided they are gasifiable and vaporizable. The furnace can be easily adapted to various outflow rates since there is no danger of backfire, because there is no premixing of the reacting products. Moreover, owing to the possibility and ease of adjustment of the rates and ratios of the reactants (and, therefore, of the duration of contact), it is possible, as already mentioned, to shift the equilibrium of the cracking reaction in such a manner as to produce a larger quantity of determined unsaturated hydrocarbons as compared with other hydrocarbons.

Example 1 The furnace is made of a zirconium refractory material in the upper part of which is a burner which faces a combustion chamber having a final delivery section of 5 x 500 mm. and a height of 150 mm. The hydrocarbon to be cracked is conveyed onto the laminar stream 4 of hot gases by means of two laminal injectors having outlet sections of 5 x 500 mm. mounted on both sides of the combustion chamber.

The fuel gas consists of pure hydrogen with a flow rate of 80 Nm. /h. This signifies cubic meters per hour as recalculated for 760 mm. of mercury pressure and 0 C. The combustion supporter is pure oxygen with a flow rate of 35 Nmfi/h. The hydrocarbon to be cracked is a liquefied natural gas with a carbon index of 3.4 and an unsaturated products content of 17%. Its flow rate is 45 kg./h. The gas produced contains 8% acetylene and 12%-ethylene by volume, in addition to methane and other saturated and unsaturated hydrocarbons, hydrogen, CO and C0 The total acetylene-ethylene yield, expressed as kg./kg. of liquefied gas employed is of 68%.

The oxygen and hydrogen were preheated to 500 C. and the liquefied gas to 350 C.

Example 2 The furnace is as in Example 1. The fuel gas consists of pure hydrogen with a fiow rate of 70 NmF/h. The combustion supporter is pure oxygen with a flow rate of 40 Nm. /h. 1

The hydrocarbon to be cracked is liquefied natural gas, as in Example 1, with a flow rate of 45 kg./h. The gas produced contains 12% acetylene and 6% ethylene by volume, in addition to methane and other normal gases. The preheating temperatures are 500 C.' for oxygen and hydrogen and 350 C. for the natural gas. The total acetylene-ethylene yield is by weight based on the hydrocarbon.

Example 3 I The furnace of Example 1 is used in this example. The fuel gas consists of pure hydrogen with a flow rate of 70 Nmfi/h. The combustion supporter is pure oxygen with a flow rate of 48 Nm. /hr. V

The hydrocarbon is the same as in Example 1, with a flow rate of 45 kg./h. The gas produced contains 10.5% acetylene and 2% ethylene by volume, in addition to the usual gases. The preheating temperature is 500 C. for oxygen and hydrogen and 350 C. for the liquefied natural gas. The total acetyleneethylene yield is 47% by weight based on the hydrocarbon.

- Example 4 The furnace is the same as that in Example 1, except that the combustion chamber has a final section of 8 x 500 mm. The fuel consists of pure hydrogen and the combustion supporter is air, with flow rates of 40 and 120 Nm. /h., respectively. The hydrocarbon is the same as in Example 1. Its

flow rate is 40 kg./h. The proportions of acetylene and ethylene in the product gases amounts to 4.5% and 5% by volume, respectively. The total yield amounts to 59%. r

The preheating temperature is 500 C. for hydrogen, 650 C. for air and 350 C. for the liquefied gas.

Example 5 The furnace is the same as that of Example 1, except that the combustion chamber has a length of 270 mm. The fuel gas consists of 55% hydrogen, 30% carbon monoxide and 15% methane, introduced at a flow rate of Nm. /h. The combustion supporter consists of pure oxygen, with a flow rate of 47 Nm. /h. The hydrocarbon to be cracked is that of Example 1.

The gas produced contains 7% acetylene and 9.5% ethylene by volume, with a total yield of 62%.

The fuel gas and the combustion supporter are preheated to 500 C. and the hydrocarbon to 400 C.

Example 6 The furnace is the same as in Example 5. The fuel gas, preheated to 500 (3., is the same as in Example 5,

assuage with a flow rate of 45 NmF/h. The combustion supporter is air, preheated to 500 C., with a how rate of 130 Nm. /h.

The hydrocarbon flow rate is 35 kg./h. as in Example 1.; its preheating temperature is 350 C. The gases produced contain 4% acetylene and 7% ethylene by volume. Total yield 57%.

Example 7 Example 8 l The furnace is the same as in Example 1. The fuel gas consists of pure hydrogen. It is not preheated. It is introduced into the furnace at a flow rate of 85 Nmfi/h. The. combustion supporter is pure oxygen, not preheated, and. introduced into the furnace. at the flow rate of 38 Nm. /h. The hydrocarbon to be cracked is a gasoline having a distillation range of 30 to 90" C. evaporated and heated to 360.C.; it is introduced into the furnace at the. flow rate of 35 -kg./h.

The gases produced contain 14% acetylene and 11% ethylene. by volume, in addition to methane, low ethane, amounts, C0, C and hydrogen. Total acetylene-ethylone yield 78%.

Example 9 The furnace is the same as in Example 5. The fuel gas contains hydrogen, methane and. carbon monoxide. It is preheated to 500 C. and introduced at a flow rate of 40 Nm. ./h. i

The combustion supporter is enriched air containing 43% oxygen. It is preheated to 500 C. and introduced intothe furnace at the. flow rate of 85 Nmfi/h.

The hydrocarbon to be cracked is a gasoline having-a distillation range of 30 to 105 C., evaporated and heated to 380 C. and introduced into the furnace at the flow rate of 30 kg./h. The. gases produced contain 6.5% acetylene and 4% ethylene by volume. r The total yield amounts to 48% by weight, referred to the gasoline introduoed into the furnace.

Example 10 The furnace is the same as in Example 1. The fuel gas consists of'hydrogen, carbon monoxide and methane, and is introduced into the furnace at the flow rate of 75 NmP/h. The combustion supporter is oxygen with a flow rateof 36 Nm. /h. The hydrocarbon to be cracked is gasoline distilling between 30 and 105 C'., evaporated and preheated to 350 (land introduced into the furnace at the flow rate of 45 k'g/h. The gases produced contain 8% acetylene and 14% ethylene by volume, in ad-di tion to methane, propylene, carbon monoxide, carbon dioxide and hydrogen.

The total acetylene-ethylene yield amounts to 58% by weight.

Example 11 The furnace is the same as in. Example 5. The fuel gas, consisting of hydrogen and methane, is preheated to 500 C. and introduced into the furnace at the flow rate of 7 0 Nin /h. The combustion supporter is oxygen with a flow rate of 43 Nm. /'h-. The hydrocarbon to be cracked is. a gasoline distilling at between 90 and 175 C., evaporated and heated to 370 C., introduced into the furnaceat the flow rate of 35 kg./ h. The gases. produced contained 9% acetylene and 7.5% ethylene; total yield 51% by weight.

Example 12 The furnace is the same as in Example 1. The fuel gas consists of hydrogen, carbon monoxide and methane, preheated to 500 C. and introduced into the furnace at the flow rate of 60 Nmfi/h. The combustion supporter is pure oxygen at a flow rate of 45 Nm. /h. The hydrocarbon to be cracked is a gasoline distilling at between 30 and 105 C., preheated to 380 C. and introduced into the furnace at the flow rate of 30 -kg./h.

The gases produced contain 9% acetylene and 2% ethylene by volume, with a total yield of 45%.

Example 13 The furnace is the same as in Example 5. The fuel. gas consists of a liquefied natural gas having a carbon index of 3.4 and an unsaturated product proportion of 27%, preheated to 350 C. and introduced into the. fur.- nace at the. flow rate of 15 kg./h. The combustion sup-. porter is pure oxygen, at a flow rate of 50 Nm. /h. The hydrocarbon to be cracked is a gasoline distilling at between 90 and 175 C., preheated to 360 C. and. introduced into the furnace at the flow rate of 40 kgjh. The gases produced contain 7% acetylene and 8% ethylene by volume, in addition to methane, carbon monoxide. and hydrogen. The total yield amounts to 48% by weight, calculated on the gasoline.

Example 14 The furnace used was made of zirconium refractory and carried at top a burner opening into a combustion. chamber 500 mm. high and having final delivery crosssection of 25 mm. x 500 mm. i

The hydrocarbon to be cracked is introduced into the. sheet of hot gases by means of two laminar (sheet) injectors with 10 mm. x 500 mm. outlet cross section. mounted at the sides of the. combustion chamber. The

combustible gas is pure H its flow rate is 400 Nmfi/h;

The hydrocarbon to be cracked is liquefied. natural gas with carbon index 3.4 and with 17% unsaturated product content; its flow rate is 175 kg./h. The gas produced contains 11% of acetylene by volume in addition to. methane, other saturated and unsaturated hydrocarbons, hydrogen, carbon monoxide and carbon dioxide. The overall yield of ethylene plus acetylene is 61% as ex.- pressed in kg./kg. of liquefied natural gas. and the hydrogen are preheated to 500 C.; the liquefied. natural gas is preheated to 350 C.

Example 15 The furnace of Example 14 is used. The combustible gas is pure hydrogen with flow rate of 350* Nm. /h., the combustion supporter is pure oxygen with flow rate 'of. 220 Nm. /h. The hydrocarbon is the same liquefied gasof Example 14, its flow rate is 225 kg./h. The gas produced contains 11% of acetylene, 5.5% of. ethylene by volume in addition to methane, other saturated and un-- saturated hydrocarbons, hydrogen, carbon monoxide and carbon dioxide. The overall yield of ethylene plus acetylene is 56% by weight based on the hydrocarbon. The oxygen and the hydrogen were preheated to 500 C.; the liquefied natural gas, to 350 C.

Example 16 The furnace of Example 14 was used. The final outlet cross-section for the hot gases was 55 mm. x 500 mm. The hydrocarbon was fed with two laminar (sheet) injectors with outlet cross-section of 10 mm. x 500 mm. The combustible gas was a mixture of of hydrogen and 20% of methane. The combustion supporter was pure oxygen. The hydrocarbon to be cracked was gasoline having a distillation range of 30 to C'., evaporated and The oxygen.

l i heated to 320 C. The combustible gas was preheated to 400 C. and the combustion supporter was fed, at 25 C. The flow rates were of the order of 650 Nmfi/h. combustible gas, 450 Nm. /h. oxygen and 410 kg./h. gasoline. The gas produced contained acetylene and 8% ethylone by volume, with total yield of 65% by weight.

Example 17 The furnace of Example 14 is used. The laminar flame or the final exit cross-section of the hot gases is 80 mm. x 500 mm. The two laminar injectors for feeding the hydrocarbon have outlet cross-section of 14 mm. x 500 mm. The combustible gas is a mixture of 80% hydrogen and 20% methane, and is pre-heated to 400 C. The combustion supporter is pure oxygen and is passed to the burner at 25 C. The hydrocarbon to be cracked is gasoline having a distillation range of 115 C. to 190 .C., evaporated and heated to 420 C. The flow rates are 950 Nm. /h. of combustible gas, 650 Nm. h. of oxygen, 600 kg./h. of gasoline. The produced gas contains 9.5% of acetylene and 8% of ethylene by volume, with 59.5% total yield.

In the Examples 1 to 17, the hydrocarbons are introduced in superheated condition at just the pressure needed to overcome the pressure losses of the apparatus, namely, thepressure losses caused by the interstices of the burner, so as to enable introduction of said hydrocarbons. The same is true for the oxygen introduced.

The pressure in the reaction zone (zone 10 in FIG. 1) is atmospheric except for the small super-pressure required to compensate for the pressure losses of the reaction charnber, so as to allow for rapid passage of gas.

The rectangular or laminar dimensions of the flame and, subsequently, of the gases or vapours in the rectangular or laminar zone of cracking proper, can be increased by keeping constant the width of the sheet and increasing its length to the extent permitted by the resistance of the materials (refractory or metallic) employed, so as to attain an industrially interesting capacity. The industrial capacities required can be attained by connecting a number of laminar furnaces in parallel, as mentioned above.

We claim:

1. In a process for endothermal cracking of a hydrocarbon, the improvement comprising impacting an extended-surfaced wide sheet of hot combustion gas with an extended-surfaced wide sheet of a hydrocarbon to be cracked, the sheets being directed transversely to each other and intersecting along a line longitudinal to their widths, at least the major part of the heat required for the cracking being supplied by pre-heat of the hydrocarbon and the heat of the said combustion gases, said hydrocarbon being taken from the group consisting of gasoline and liquefied natural gas, the combustion gas being derived by burning a fuel taken from the group consisting of hydrogen, carbon monoxide and methane with an oxygen-contraining gas, the gases produced being abruptly chilled, the products of the process comprising acetylene and ethylene.

2. In a process for endothermal cracking of a hydrocarbon, the improvement comprising contacting an extended-surfaced wide sheet of hot combustion gas with an extended-surfaced wide sheet of a hydrocarbon to be cracked, the sheets being directed transversely to each other and intersecting along a line longitudinal to their widths, at least the major part of the heat required for the cracking being supplied by pre-heat of the hydrocarbon and the heat of the said combustion gases, said sheets comprising substantially flat planar sheets, substantially all points of any taken cross section of each of the impacting sheets having substantially the same temperature, the velocity of each of the impacting sheets being such as to provide a Reynold number for each sheet which is at least high enough to ensure turbulent flow of each sheet, the speeds of the impacting sheets being at least about 100 meters per second, the sheets each contributing their in- .8 dividual kinetic energies to the impaction, the hydrocarbon" sheet being confined laterally so that its thickness is not greater than about 14 millimeters, the sheet of hot combustion' gas being confined laterally so that itsthickness is not greater thanabout millimeters at the zone'of'impaction, the width of each of said sheets being'at least about 500 millimeters. 7 I 3. In a process for endothermal cracking of a hydrocarbon, the improvement comprising contacting an extended-surfaced wide sheet of hot combustion gas with an extended-surfaced wide sheet of a hydrocarbon to be cracked, the sheets being directed transversely to eacli other and intersecting along a line longitudinal to their widths, at least the major part of the heat required for the cracking being supplied by pre-heat of the hydrocarbon and the heat of the said combustion gases, the sheet of hot combustion gas being curved, substantially all pointsof any taken cross section of each of the impacting sheets having substantially the same temperature, the velocity of each of the impacting sheets being such as to provide a Reynolds number for each sheet which is at least high enough to ensure turbulent flow of each sheet, the speeds of the impacting sheets being at least about meters per second, the sheets each contributing their individual kinetic energies to the impaction, the hydrocarbon sheet being confined laterally so that its thickness is not greater than about 14 millimeters, the sheet of hot combustion gas being confined laterally so that its thickness is not greater than about 80 millimeters at the zone of impaction; the width of each of said sheets being at least about 500 millimeters. p 4. An apparatus for the endothermal cracking of a hydrocarbon, comprising a burner having mutually converging narrow passageways for fuel gas and oxygen-' containing gas, respectively, the passageways each having an extended dimension in a common direction transverse to their narrow dimension, to project the fuel gas and oxygen-containing gas in the form of wide contiguous sheets which burn to form a wide flame, and to form a wide sheet of hot combustion gas, a structure providing a narrow combustion chamber for the burner gases, a transversely directed narrow passageway in said structure for introduction of a Wide sheet of hydrocarbon to be cracked, for impaction with the burner gases, the latter passageway having an extended width dimension in a direction which is transverse to its narrow dimension and is longitudinal to the width of said sheet of combustion gases, whereby said sheets impact and intersect along a line longitudinal to their widths, the narrow dimension of said passageway being not more than about 14 millimeters at the outlet thereof, the narrow dimension of the combustion chamber being not more than about 80 millimeters across at the line of impaction, the widths of the combustion chamber and the passageway being at least about 500 millimeters.

5. An apparatus for the endothermal cracking of a hydrocarbon, comprising a burner having mutually converging narrow passageways for fuel gas and oxygen-contain ing gas, respectively, the passageways each comprising a narrow slit having an extended width dimension in a common direction transverse to their narrow dimension, to. project the fuel gas and oxygen-containing gas in the form of wide contiguous sheets which burn to form a wide flame, and to form a wide sheet of hot combustion gas, a

structure providing a combustion chamber for the burner gases in the form of a narrow slot whose width extends" in said common direction, two opposite and transversely directed narrow passageways in said structure for introduction of a wide sheet of hydrocarbon to becracked,

each of the latter passageways having an extended width longitudinal to their widths, the narrow dimension of the slot of the combustion chamber being not more than about" 80 millimeters across at the line of impaction, the narrow spouses dimension of said transverse passageways being not more than about 14 millimeters at the outlets thereof.

6. An apparatus for the endothermal cracking of a hydrocarbon, comprising a burner having narrow passageways for fuel gas and oxygen-containing gas, respectively, the passageway each having an extended dimension in a common direction transverse to their narrow dimension, to project the fuel gas and oxygen-containing gas in the form of wide contiguous sheets which burn to form a wide flame and to form a wide sheet of hot combustion gas, a structure providing a combustion chamber for the burner gases, a transversely directed narrow passageway in said structure for introduction of a wide sheet of hydrocarbon to be cracked, the latter passageway having an extended width dimension in a direction which is transverse to its narrow dimension and is longitudinal to the width of said sheet of combustion gases, whereby said sheets intersect along a line longitudinal to their widths.

7. An apparatus for the endothermal cracking of a hydrocarbon, comprising a burner having narrow passageways for fuel ga and oxygen-containing gas, respectively, the passageways each comprising a narrow slit having an extended Width dimension in a common direction transverse to their narrow dimension, to project the fuel gas and oxygen-containing gas in the form of wide contiguous sheets which burn to form a wide flame and to form a Wide sheet of hot combustion gas, a structure providing a combustion chamber for the burner gases in the form of a narrow slot whose width extends in said common direction, two opposite and transversely directed narrow passageways in said structure for introduction of a wide sheet of hydrocarbon to be cracked, the latter passageways having an extended width dimension in a direction which is transverse to their narrow dimensions and is longitudinal to said common direction, whereby said sheets intersect and impact along a line longitudinal to their widths, the narrow dimension of the slot of the combustion chamber being not more than about 80 millimeters across at the line of impaction, the narrow dimension of said transverse passageways being not more than about 14 millimeters at the outlets thereof.

8. The apparatus defined in claim 6, and means for abruptly cooling the exit gases, to produce acetylene and ethylene.

9. In a process for endothermal cracking of a hydrocarbon, the improvement comprising impacting an extended-surfaced wide sheet of hot combustion gas with an extended-surfaced wide sheet of a hydrocarbon to be cracked, the sheets being directed transversely to each other and intersecting along a line longitudinal to their widths, at least the major part of the heat required for the cracking being supplied by pre-heat of the hydrocarbon and the heat of the said combustion gases, substantially all points of any taken cross section of each of the impacting sheets having substantially the same temperature, the velocity of each of the impacting sheets being such as to provide a Reynolds number for each sheet which is at least high enough to ensure turbulent flow of each sheet, the speeds of the impacting sheets being at least about 100 meters per second, the sheets each contributing their individual kinetic energies to the impaction, the hydrocarbon sheet being confined laterally so that its thickness is not greater than about 14 millimeters, the sheet of hot combustion gas being confined laterally so that its thickness is not greater than about 80 millimeters at the zone of impaction, the width of each of said sheets being at least about 500 millimeters.

10. In a process for endothermal cracking of a hydrocarbon the improvement comprising separately projecting contiguous streams of fuel and oxygen in the form of extended-surfaced sheets to form upon burning an extended-surfaced wide flame sheet, impacting opposite faces of said flame sheet with extended-surfaced wide sheets of a hydrocarbon to be cracked, the sheets of hydrocarbon being directed toward each other and each intersecting 10 the sheet of flame longitudinally to the widths of all the sheets, at least the major part of the heat required for the cracking being supplied by pre-heat of the hydrocarbon and the heat of the said combustion gases, the sheets being flat planar sheets, substantially all points of any taken cross section of each of the impacting sheets having substantially the same temperature, the velocity of each of the impacting sheets being. such as to provide a Reynolds number for each sheet which is at least high enough to ensure turbulent flow of each sheet, the speeds of the impacting sheets being at least about 100 meters per second, the sheets each contributing their individual kinetic energies to the impaction, each of the hydrocarbon sheets being confined laterally so that its thickness is not greater than about 14 millimeters, the sheet of flame being confined laterally so that its thickness is not greater than about millimeters at the zone of impaction, the width of each of said sheets being at least about 500 millimeters.

11. In a process for endothermal cracking of a hydrocarbon, the improvement comprising separately projecting contiguous streams of fuel and oxygen in the form of extended-surfaced sheets, to form upon burning an extended-surfaced wide flame and a resultant, extendedsurfaced wide sheet of hot combustion gas, impacting opposite faces of said extended-surfaced sheet of hot combustion gas with extended-surfaced wide sheets of a hydrocarbon to be cracked, the sheets of hydrocarbon being directed toward each other and each intersecting the sheet of combustion gas along a line longitudinal to the widths of all the sheets, at least the major part of the heat required for the cracking being supplied by pre-heat of the hydrocarbon and the heat of the said combustion gases, the sheets being fiat planar sheets, substantially all points of any taken cross section of each of the impacting sheets having substantially the same temperature, the velocity of each of the impacting sheets being such as to provide a Reynolds number for each sheet which is at least high enough to ensure turbulent flow of each sheet, the speeds of the impacting sheets being at least about meters per second, the sheets each contributing their individual kinetic energies to the impaction, each of the hydrocarbon sheets being confined laterally so that its thickness is not greater than about 14 millimeters, the sheet of hot combustion gas being confined laterally so that its thickness is not greater than about 80 millimeters at the zone of impaction, the width of each of said sheets being at least about 500 millimeters.

12. In a process for endothermal cracking of a hydrocarbon, the improvement comprising separately projecting contiguous streams of fuel and oxygen in the form of extended-surfaced sheets, to form upon burning an extended-surfaced wide flame and a resultant extendedsurfaced wide sheet of hot combustion gas, impacting opposite faces of said extended-surfaced sheet. of hot combustion gas with extended-surfaced wide sheets of a hydrocarbon to "be cracked, the sheets of hydrocarbon being directed toward each other and each intersecting the sheet of combustion gas along a line longitudinal to the widths of all the sheets, at least the major part of the heat required for the cracking being supplied by pre-heat of the hydrocarbon and the heat of the said combustion gases, said hydrocarbon being taken from the group consisting of gasoline and liquefied natural gas, the combustion gas being derived by burning a fuel, taken from the group consisting of hydrogen, carbon monoxide, and methane, with an oxygen-containing gas, the gases produced being abruptly chilled, the products of the process comprising acetylene and ethylene, the sheets being flat panar sheets, substantially all points of any taken cross section of each of the impacting sheets having substantially the same temperature, the velocity of each of the impacting sheets being such as to provide a Reynolds number for each sheet which is at least high enough to ensure turbulent flow of each sheet, the speeds of the greater than about 14 millimeters, the sheet of hot com- 5 bustion gas being confined laterally so that its thickness is not greater than about 80 millimeters at the zone of impaction, the Width of each of said sheets being at least about 500 millimeters.

References Cited in the file'of this patent 1 UNITED STATES PATENTS Eckholm et al. May 20, 195 2 Heller May 29, 1955 Seed Sept 22, 1959 FOREIGN PATENTS 7 Great Britain Dec. 30, 1935 

1. IN A PROCESS FOR ENDOTHERMAL CRACKING OF A HYDROCARBON, THE IMPROVEMENT COMPRISING IMPACTING AN EXTENDED-SURFACED WIDE SHEET OF HOT COMBUSTION GAS WITH AN EXTENDED-SURFACED WIDE SHEET OF A HYDROCARBON TO BE CRACKED, THE SHEETS BEING DIRECTED TRANSVERSELY TO EACH OTHER AND INTERSECTING ALONG A LINE LONGITUDINAL TO THEIR WIDTHS, AT LEAST THE MAJOR PART OF THE HEAT REQUIRED FOR THE CRACKING BEING SUPPLIED BY PRE-HEAT O THE HYDROCARBON AND THE HEAT OF THE SAID CUMBUSTION GASES, SAID HYDROCARBON BEING TAKEN FROM THE GROUP CONSISTING OF GASOLINE AND LIQUEFIED NATURAL GAS, THE COMBUSTION GAS BEING DERIVED BY BURNING A FUEL TAKEN FROM THE GROUP CONSISTING OF HYDROGEN, CARBON MONOXIDE AND METHANE WITH AN OXYGEN-CONTRAINING GAS, THE GASES PRODUCED BEING ABRUPTLY CHILLED, THE PRODUCTS OF THE PROCESS COMPRISING ACETYLENE AND ETHYLENE. 